She turned up in Gloucestershire in 1817, claiming to be Princess Caraboo from the island of Javasu - saying she had been kidnapped by pirates before escaping and making her way to England.
Princess Caraboo's invented language fooled several experts
And the fact that Mary Willcocks' tale was completely invented arguably makes her story no less remarkable.
The young woman who said she was a princess from a faraway island was later proved to be a 26-year-old cobbler's daughter from Devon, whose exotic foreign dialect had been a fictitious language.
But her place in Bristol folklore has been recognised this week with the unveiling of a blue plaque in a street in Bedminster, the suburb where she spent the last 11 years of her life.
The supposed princess arrived in the Gloucestershire village of Almondsbury, near Bristol, on 3 April 1817, wearing a black turban and black dress, with her possessions wrapped up in a small bundle.
Publicity her downfall
She appeared exhausted and starving and was speaking a language nobody in the village could understand.
The villagers thought she was a foreign beggar and she was taken to the home of Samuel Worrall, the local county magistrate.
His wife was keen to find out more about her and, after taking her in to stay, managed to work out that her name was Caraboo and she had come to England by ship.
After various attempts to identify the language she was speaking, a Portuguese sailor said he understood the language and translated Caraboo's story.
He said she was a princess from an island called Javasu who had been abducted by pirates and taken on a long journey by sea which ended when she jumped overboard in the Bristol Channel.
Once the Worralls realised they had a foreign princess in their house, they began to exploit the fact, inviting guests round to be entertained by the exotic Caraboo and her strange language and behaviour.
Newspapers began to ran stories on her, but it was this publicity which would bring Miss Willcocks' spell as a princess to an end.
Phoebe Cates played the part of Princess Caraboo on film
After two months, the owner of a Bristol lodging house saw a picture of her in a newspaper and realised "Princess Caraboo" was the same young woman who had stayed with her earlier in the year - and entertained her daughters with an invented language.
But rather than being the end of her time in the limelight, the truth extended it further, with Miss Willcocks now being hailed as a working class heroine who had deceived high society.
She was sent to America and spent seven years there, but found herself hailed a heroine in her Princess Caraboo role and made public appearances as her - just as she did when she returned to England in 1824.
She spent the last few years of her life back in Bristol, making a living selling leeches to the city's hospital, before dying at the age of 75 in 1864.
A film of Mary Willcocks' life was made by Disney in 1994 - titled Princess Caraboo and starring Kevin Kline and Jim Broadbent and with Phoebe Cates in the title role.
'Dared to escape'
Brian Haughton, a historian who has written about Princess Caraboo, agrees that she is worthy of recognition - and was as much a class-warrior inspiration as a cheeky hoaxer.
He said: "In an age when women were second class citizens, and working class women had practically no rights at all, Mary Willcocks managed to break out of her class and into high society and beat them at their own game.
"Through a combination of her own unique talents and her appeal to the romanticism of the upper class, Mary was treated like the exotic princess she claimed to be.
"This Devon servant girl achieved this during a period of English history when people were being transported to Australia for stealing a petticoat.
"That Mary dared to escape her menial position and perpetrate such a complicated hoax is, I believe, nothing short of wondrous.
"Mary Willcocks should be an inspiration to anyone who feels held back by their position in society."
Christopher Orlik, a former member of Bristol City Council who is involved in organising the city's blue plaques, agrees the hoax princess deserves her recognition.
He said: "I think she's part of Bristol's history. In an age where there was no entertainment in the way of radio, television or cinema, she provided a lot of entertainment for people, and she didn't do any harm.
"We've got 47 blue plaques now and she may not be as famous as some of the other people but she's the only one who has had a full length film made about her.
"It creates pride in the city - I'm proud to be a Bristolian and I'm proud to be from where Princess Caraboo lived and to walk on the streets she walked on."